The invention relates to a system for filing cinematographic film material. The invention also relates to a film scanner, a display device for such a filing system, the data carrier used, and to a filing method.
Due to ageing, the picture and sound quality, particularly of very old films, deteriorates to such an extent that the master copy is no longer usable. To avoid complete loss, photographic copies may be made over longer periods of time, but every copying process then also involves a loss of quality. To maintain at least the quality which is available, cinematographic films are filed as digital copies on appropriate data carriers such as magnetic tapes. It is true that magnetic recordings have a limited lifetime, but copies can be made without any loss from digitally stored information.
To manufacture a digital master for filing a cinematographic film, the picture information stored on the film is scanned in film scanners by means of a scanning device, and the sound information on an optical sound track is scanned by means of a separate sound-scanning device. In so far as the film scanner used ensures electronic stabilization of the frame position, for example, also the edges of each film frame are scanned with the scanning device or, for example, the positions of the sprocket holes are scanned as reference marks by means of scanning devices provided for this purpose. The offset is computed individually for each frame from the deviation of the reference marks, and the picture position of each frame scanned is corrected by means of, for example, a digital video effect apparatus, before it is supplied for further processing or storage. Similarly, the sound scanning values obtained during sound scanning are converted into an analog or digital audio signal before they are supplied. Any further information provided on the film, such as, for example, film time code and key code may be scanned and their information contents may be stored as digital data equivalents.
Since it is generally desired to save as much cinematographic art as possible from further deterioration, the preservation of film material in the state in which it is found is in the limelight of interest, whereas a time-consuming and capital-intensive restoration for the purpose of preserving a maximal number of films is postponed. Generally, the film material is done away with after filing, for at a later stage, for example, during restoration, it has suffered from a further loss of quality anyway, or may even have become unusable.
It is an object of the present invention to provide a system for filing cinematographic films, with which the optimal quality state is ensured at any time of restoration.
In a filing system, this object is achieved by way of the characteristic display at a later stage, particularly for purposes of restoration by means of film material digitally filed in the conventional manner, may not benefit from all technical facilities of the display and restoration technique at this future stage, because the current filing technique may have led to an irretrievable loss of given information required for techniques which have not been developed, or even conceived yet. Storage of the scanning values of a maximal amount of individual information provided on a cinematographic film at least offers an opportunity to evaluate the information at a later stage as if the film were scanned at the time of display or restoration. In this method, it is not necessary to stabilize the frame position, because information for later frame position correction is maintained. Particularly the storage of the optical sound track as its digitized optical image allows a quasi-optical rectification, for example, by means of two-dimensional filtering of the optical sound track for the purpose of covering film dirt and film scratches, as is already conventional practice for the film frames themselves, but not yet for the optical sound track.
It is therefore particularly advantageous to scan the film throughout its width and preferably continuously in the film travel direction, i.e. without any interruption of scanning in between the frames, because all optically detectable information is filed in this way, particularly information about the film edges and the sprocket hole position, and information which may have been provided between the sprocket holes, such as, for example, film time code, key code, in the intermediate areas of the sound tracks, in the area of the frame line, as well as information about the position of the boundaries of the individual frames and possibly other marks provided outside the frames and optical sound tracks.
Due to the enormous quantity of data for this first-mentioned solution, it is proposed for reasons of economy to detect at least the most essential information by means of separate scanning sensors and store this information as digitized optical images, rather than store only the original analog or digital information contents determined from the scanning value, as has hitherto been conventional practice. In addition to the hitherto customary scanning values of the film frames, these information contents would also comprise at least the scanning values of the optical sound track and possibly the scanning values of at least a sprocket hole assignable to each film frame.
This variant of the invention has the advantage that a split-up of the scanning device into a plurality of scanning devices which can be arranged individually and assigned to scanning given areas of a film to be scanned imposes less stringent requirements as regards the resolution of the scanning devices than would be the case for a single scanning device.